[34] Under no circumstance does the stomach rise up, as Bichat calls it. We have, in a preceding note, explained the ordinary motions of this viscus, in a state of vacuity, during digestion and under the influence of an internal or external stimulus. None of these motions are sufficient to produce that sudden and energetic expulsion which characterizes vomiting. The opinion that the stomach rises up in vomiting originated in a time of ignorance, and we ought not to be astonished that it should find advocates even in our day. This has not however been uniformly adopted; Bayle and P. Chirac opposed it by experiments; Senac, Van Swieten and Duverney declared themselves against it; but Haller, by adopting it, suddenly changed the views and removed the uncertainty of a great number of physiologists, who, not taking the labour of making experiments for themselves, loved to repose on the faith of a celebrated name. In physiology the opinions of Haller are certainly entitled to very great weight; this is because this wise observer, before announcing them as a general proposition, was accustomed to repeat many times the experiments on which he founded them; but in this case he did not sufficiently question the use of the stomach in vomiting. He has made four experiments only, less for the purpose of satisfying himself that the phenomenon existed, than to see it such as he supposed it. It is very difficult, even for the best mind, to divest itself in observing, of the ideas previously received without examination. It may then be believed, that Haller in this way saw but superficially. These considerations determined me some years since, to satisfy myself of what takes place in vomiting, and of the part which the stomach performs in it. I shall relate briefly the experiments which I tried on the subject. The first was made on a dog of middling size, whom I had made to swallow six grains of emetic. When this medicine had excited nausea, I cut through the linea alba opposite the stomach, and introduced my finger into the abdomen. At each nausea, I felt it very powerfully compressed above by the liver, which the diaphragm pushed down, and below by the intestines, which were compressed by the abdominal muscles. The stomach also appeared to me to be compressed; but instead of feeling it contract, it appeared to me, on the contrary, to increase in size. The nauseas became more frequent, and the more marked efforts, which precede vomiting, appeared. Vomiting finally took place, and then I felt my finger pressed with a force truly extraordinary. The stomach rid itself of a part of the aliments it contained; but I distinguished no sensible contraction in it. The nausea having ceased for a short time, I enlarged the opening in the linea alba, for the purpose of observing the stomach. As soon as the incision was enlarged, the stomach presented itself at it,